1. Field of the Invention
This invention relates to a bar stock feed and support apparatus for a multiple spindle automatic lathe, and more particularly, to a fluid operated, multiple-tube bar stock feeder using fluid to support pieces of bar stock.
2. Description of the Related Art
High-production multiple-spindle lathes or screw machines are typically equipped with automatic bar stock feeders for advancing stock. It has been proposed in bar stock feeders to support the rotating bar stock on a film of oil within a guide tube. Bar feeders using such an oil film are usually called hydraulic, hydrodynamic or hydrostatic bar feeders. The oil film reduces friction, dampens vibrations, reduces noise, centers the bar stock, and allows higher turning speeds. The higher speeds allow higher production. The centering and reduced vibration results in improved surface finishes.
Hydraulic bar feeders have been used with varying degrees of success. In one design, bars were advanced through guide tubes with a reciprocating friction feeder connected to the lathe. The guide tubes were flooded with oil to achieve the oil film support. Removable caps were provided at the rear end (the end opposite the lathe headstock) for reloading the guide tubes with bars. A shortcoming of this design was that oil poured out of the tubes when the cap was removed for reloading. The oil could be recovered with a catch basin but still created a messy work area.
In another design, pistons were provided at the rear end of the guide tubes for advancing the bar stock. The pistons overcame the need for a conventional mechanical bar stock advancer and its many moving parts on the lathe. The guide tubes were flooded with oil which was allowed to flow through a restricted opening in the pistons. This design permitted reloading of the guide tubes from the front end, which avoided the problem of having to remove the pistons for reloading. That is, the entire stock magazine was pivotable such that the front end of the guide tubes could be laterally pivoted away from the head stock for reloading. One shortcoming if this design is that reloading had to be done from the side of the machine rather than from its end. This interfered with the operator and caused inconvenience where many machines were positioned in side-to-side rows. Thus, there is a need for a bar stock feeder using an oil film to support the stock, fluid actuated pistons to advance the stock, and the guide tubes which can be reloaded from their rear end without having oil pour out of the tubes during reloading.